O Ci

MeOH

Rx3 foMe /

Comb. Chemistry

Me O Cl

Scheme 9

3 h. Evaporation yielded the secondary amine 17 as hydrochloride.The isolated yield varied from 70 % to 95 %, depending on the type of amine.

Another benzyl-based method was developed for the preparation of secondary amides on solid support. Release of the product after treatment with TFA required an electron-rich benzyl linker (Scheme 10). The secondary amides 24 were obtained quantitatively, and in high purity [21],

As a further example of a benzyl-based attachment of amines, the p-benzyloxybenzy-lamine resin (25) was prepared and applied to the synthesis of compounds of type 26 [22]. The reaction involved the formation of a Schiff base as well as a Yb(OTf)3-catalyzed addition of silyl enolates. The cleavage from the support was achieved by a DDQ-oxidation (Scheme 11).

3.1 Linkers for Solid-Phase Organic Synthesis and Combinatorial Approches on Solid Support 57 OMe

Scheme 10

Yb(OTf)3

n^FT

Rv_/OSiMe3

Yb(OTf)3

R3 R4

R1 O 26

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